
theorem Th310:
Sum digits(418,10) = 13
proof
  thus Sum digits(418,10) = Sum <%8,1%>+Sum <%4%> by Th309,AFINSQ_2:55
  .= (8 + 1) + Sum <%4%> by AFINSQ_2:54
  .= 9 + 4 by AFINSQ_2:53
  .= 13;
end;
